Field
The disclosed concept pertains generally to electric loads and, more particularly, to methods of determining power consumption thereof. The disclosed concept also pertains to systems for determining power consumption of electric loads.
Background Information
Of the primary electricity used by commercial buildings, about 37% is consumed by plug-in electric loads (PELs), also known as miscellaneous electric loads (MELs). This use is expected to grow by 78% between 2008 and 2030. PELs are defined as all non-mains connected electric loads in a building and include a variety of electrical devices such as, for example and without limitation, refrigerators, computers, food preparation appliances and space heaters/fans. The total energy consumption of these “plug-in” devices is often overlooked.
Several studies indicate that an effective management of PELs could potentially improve energy savings of buildings by up to about 10% to 30% of their usage. However, the development of widely applicable energy saving solutions for PELs is difficult mainly because of the limited visibility of PELs' energy usage in today's buildings. Knowing the energy consumption by types and categories of PELs is needed to overcome the above difficulties. Thus, developing a cost-effective, nonintrusive appliance load monitoring and identification technology at the load level (also known as the “appliance-level”) is desired.
In buildings, electric power can be supplied to a PEL directly through a wall outlet, or through a power strip that is plugged into a wall outlet in order to distribute power to multiple outlets of the power strip. The latter scenario is more commonly adopted by users to enable the wall outlet to simultaneously supply power to more than a couple of PELs.
A technology that is capable of decomposing/decoupling power consumption of PELs by only measuring the aggregated electric signals at the wall outlet level is often desired as a cost-effective, nonintrusive load monitoring and identification (NILM) solution. An early example NILM apparatus and method is disclosed by U.S. Pat. No. 4,858,141.
Many researchers worldwide have been working toward a new generation of electricity measurement systems that are capable of providing disaggregated data about consumption at the individual appliance or device level. In general, the features and the disaggregation approaches that are used to monitor down to the appliance-level or the device-level can be categorized into three groups: (1) detecting the sharp changes in both the aggregate real and reactive power consumption; (2) current consumption and startup characteristics; and (3) voltage signatures.
Even though NILM technologies have been developed since the 1980s, no known commercially available disaggregation method is believed to be easily deployable, highly accurate, and cost effective. Most of the known methods require either an observation of hours or even longer, and some other methods require central processing units (CPUs) and operating systems to run artificial intelligence algorithms, which usually need an expensive platform to support the implementation.
There is room for improvement in methods of estimating power consumption of a plurality of electric loads.
There is also room for improvement in systems for estimating power consumption of a plurality of electric loads.